Insulating varnish, also called insulating coatings, is a kind of coating with excellent electrical insulation. It has good electrochemical properties, thermal properties, mechanical properties and chemical properties, mostly varnishes, but also colored paints. Insulating varnish is a special paint in the paint category. Insulating varnish is an important insulating material based on high molecular polymer that can be cured into an insulating film or insulation under certain conditions.
Composition of insulating varnish
Insulating varnish is composed of base material, flame retardant, curing agent, pigment and filler, and solvent, etc.
BinderThe base material is composed of polyamide resin, polyesterimide resin, polyurethane, epoxy resin, bismaleimide resin, silicone resin and other resins
Flame retardantFlame retardants are divided into reactive flame retardants and additive flame retardants; according to the composition can be divided into inorganic flame retardants and organic flame retardants
PigmentThe purpose of adding pigments and fillers to the varnish is to improve the performance of the paint and formulate it into the required color. Commonly used pigments and fillers are white, iron oxide red, carbon black, chrome yellow, mica powder, talc, barium sulfate, calcium carbonate, and silica
HardenerCuring agent (or initiator) is an indispensable component of most insulating coatings. In flame-retardant coatings based on epoxy resin, curing agents such as amine adducts, acid derivatives, and synthetic resins must be added; in flame-retardant coatings based on vinyl resin, an appropriate amount should be added. Peroxide is used as the initiator.
AdditivesAuxiliary agent is one of the indispensable components in the manufacture, storage, construction and performance improvement of insulating coatings, and is an auxiliary component of raw materials. It plays a special effect in the coating, and plays a very important role in the process and durability of the base material to form a coating film. According to its mechanism of action, it is mainly divided into curing accelerators, surfactants, rheology modifiers, stabilizers and anti-aging agents. The curing accelerator can reduce the curing temperature, accelerate the curing speed, and reduce the exothermic peak of the curing reaction. Commonly used curing accelerators are Lewis acids, Lewis bases and shuttle salts
SolventSolvents are used as the vehicle for the manufacture of coatings, which can adjust the construction viscosity of the coatings to meet the construction performance. The solvent in the coating should not react with the coating components, that is, the solvent used should be relatively inert. Commonly used solvents are aromatic hydrocarbons, alcohols, cellosolves, ketones and vinegars
Common types of insulating varnish
Impregnating varnishImpregnating varnish is divided into two categories: solvent varnish and solvent-free varnish. It is mainly used to impregnate the coils of motors and electrical appliances to fill the gaps and micropores. After curing, it can form a continuous and smooth paint film on the surface of the impregnated object. Make it bond into a hard whole. The basic requirements for impregnating paint are:
1. Low viscosity, good fluidity, high solid content, easy to penetrate and fill the impregnated material.
2. Fast curing, good drying performance, strong bonding force, thermal elasticity, and can withstand the centrifugal force of the motor when it is cured.
3. It has excellent electrical properties and chemical stability, moisture resistance, heat resistance and oil resistance.
4. It has good compatibility with conductors and other materials.
Enameled wire paintEnameled wire paint is mainly used for coating and insulation of enameled wire cores. Since the wire will be subjected to heat, chemical and various mechanical forces in the process of winding coils and embedding wires, the enameled wire paint is required to have good coating properties (that is, uniform coating) and strong paint film adhesion. The surface is smooth, soft and tough, with certain wear resistance and elasticity, good electrical performance, heat resistance, solvent resistance, and non-corrosion to conductors.
Cover varnishCover varnish is used to coat coils and insulating parts that have been immersed, and form an insulating protective layer with a uniform thickness on the surface to prevent equipment insulation from mechanical damage, atmospheric and chemical erosion, and improve surface insulation strength. Therefore, the covering paint is required to have the characteristics of fast drying, strong adhesion, hard paint film, high mechanical strength, moisture resistance, oil resistance, and corrosion resistance. Cover varnish is divided into alkyd varnish, epoxy varnish and silicone varnish according to the type of resin. Epoxy varnish has better moisture resistance, mildew resistance, internal dryness and adhesion than alkyd varnish, and has high paint film hardness. It is widely used for surface coating of electrical and electronic equipment parts in hot flash areas. Silicone varnish has high heat resistance and can be used as a covering varnish for H-class electrical appliances.
Insulating varnish can be divided into seven categories according to the insulation level: Y-level, A-level, E-level, B-level, F-level, H-level, and C-level
The details are as follows:
Heat resistance class: Maximum allowable working temperature (℃)
Class Y: 90 ℃, insulation structure composed of unimpregnated cotton yarn, silk, paper and other materials or their combination
Class A: 105°C, with an insulating structure that is impregnated or immersed in liquid dielectric (such as cotton yarn, silk, paper and other materials or their combination in transformer oil)
Class E: 120℃, insulating structure composed of synthetic organic film, synthetic organic enamel and other materials and their composition
Class B: 130°C
Class F: 155°C
Class H: 180°C, an insulating structure composed of mica, glass fiber, asbestos and other materials or their combination bonded or impregnated with a suitable resin (such as silicone resin)
Class C: above 180℃, insulated structure composed of mica, glass fiber, unimpregnated mica, ceramics, quartz, etc., or their combination, bonded or impregnated with a suitable resin
As a professional insulation material manufacturer,
YAAN specializes in manufacturing electrical insulation materials for almost 34 years.
Yanan provide the most
complete insulation varnish to the worldwide customers
